I've just taken delivery of a used Supratek Cabernet pre. This pre amp came with a few sets of tubes for rolling purposes. UX171A, 26 and the 101D. Which of these tube sets has the most warmth? Secondly for those familiar with the Cabernet, it has 2 sets of outputs one for bass and the other marked treble. I'm curious about the character of these output choices since I'm using a single stereo amp. Since I'm vision impaired, orientation to this beast is a bit daunting. Any help is most welcome.